A. Saccharides and Glycosides in General
Monosaccharides are polyhydroxy aldehydes and polyhydroxy ketones which, when unsubstituted,. have the chemical formula C.sub.n H.sub.2n O.sub.n. Monosaccharides can join together, with the loss of water, to form chains of varying lengths. The length of a saccharide chain is commonly described either by adding a descriptive prefix to its name or by stating the chain's "degree of polymerization" (abbreviated to "D.P."). For example, glucose (also known as dextrose) is a monosaccharide having a D.P. of one; sucrose and maltose are disaccharides having a D.P. of two; and starch and cellulose are polysaccharides having a D.P. of 1000 or more. The term "saccharide" encompasses unsubstituted and substituted molecules of any chain length.
Glycosides are substituted saccharides in which the substituent group is normally attached, through an oxygen, to the aldehyde or ketone carbon. Accordingly, most glycosides are considered acetals. As with the term "saccharide", the term "glycoside" defines neither the number nor the identity of the saccharide units in the molecule. To describe the number of saccharide units, the same methods are used as outlined above. To describe the identity of the saccharide units, it is common to modify the name of the saccharide unit by adding the ending "-side". For example, a glucoside is a glycoside having one or more glucose units and a fructoside is a glycoside having one or more fructose units. Accordingly, the compound having the following chemical formula is a butyl glucoside of D.P. 2. ##STR1##
Glycosides having alkyl substituent groups are an especially useful class of compounds. Short-chain (1 to 3 carbon atoms) alkyl glycosides are commonly used as intermediates in preparing polyurethane foams, medium-chain (4 to 7 carbon atoms) alkyl glycosides, and longchain (8 to 25 carbon atoms) alky) glycosides. Medium-chain alkyl glycosides are used primarily as intermediates in preparing long-chain alkyl glycosides. Long-chain alkyl glycosides are known to be surface-active due to the hydrophilicity of their saccharide portions and the lipophilicity of their long-chain alkyl portions. Therefore, it is not surprising that long-chain alkyl glycosides have often been employed as detergents, emulsifiers, wetting agents, lubricants, etc.